Calculated field in CRM updates inconsistently

Calculated field in CRM updates inconsistently

Hi,

I set up a calculated field in the CRM to essentially take a datetime field and simplify it down to a string with format of YY/MM. The formula works fine during routine interactions, but I've noticed that field updates inconsistently when doing create/updates of records via the API. Is there something else I need to do to make sure it triggers consistently?

Thanks,
Charlene